Method for the concentration and separation of sterols

Abstract

A method for the concentration and separation of a sterol-containing plant mixture employing a single, rotary, thin film horizontal evaporator for saponification of the mixture in a reaction zone, evaporation of volatile by-products, and discharge of a soap product and free sterol mixture in an evaporation zone for subsequent separation, purification, and recovery of free sterols and a soap product.

What is claimed is: 
     
       1. A method for the concentration and separation of free sterols from a feed source which comprises sterol-containing material and saponifiable material, which method comprises: a) providing a first, rotary, generally horizontal, thin film apparatus having a one end and an other end and having two external jackets to provide a first, internal, thin film reaction zone and a second, internal, thin film evaporation zone;   b) introducing the feed source into the first zone;   c) introducing an aqueous alkali solution into the first zone to saponify said saponifiable material at a controlled temperature and for a selected time to provide a saponification reaction mixture of an alkali soap, free sterols, water, and light hydrocarbons;   d) heating at a controlled temperature, the reaction mixture from the first zone reaction in the second evaporation zone;   e) withdrawing from the second zone, a light end vapor mixture comprising water and light hydrocarbons;   f) withdrawing from the second zone, a liquid slurry mixture comprising an alkali soap and free sterols; and   g) heating the liquid slurry mixture to separate and obtain a free sterol and an alkali soap product.   
     
     
       2. The method of claim 1 which includes heating the liquid slurry mixture employing a second, rotary, generally horizontal, thin film apparatus and withdrawing an alkali soap product mixture and withdrawing a vapor product of free sterols. 
     
     
       3. The method of claim 2 which includes stripping in a falling film stripper, the liquid alkali soap mixture and withdrawing a vapor residual mixture of free sterols and a sterol-free alkali soap product, and introducing the free sterol residual mixture into the second apparatus. 
     
     
       4. The method of claim 3 which includes purifying the vapor residual mixture of free sterols in a low pressure drop, fractionating column to provide an overhead product of purified free sterols. 
     
     
       5. The method of claim 1 which includes employing a rectification column for the light ends mixture withdrawn from the second zone of the first apparatus. 
     
     
       6. The method of claim 1 wherein the aqueous alkali solution comprises sodium or potassium hydroxide. 
     
     
       7. The method of claim 1 wherein the feed source comprises a plant or vegetable oil having generally greater than about 25 percent by weight of sterol-containing material. 
     
     
       8. The method of claim 1 wherein the feed material comprises free sterols or sterol esters from a deodorization process. 
     
     
       9. The method of claim 1 wherein the controlled process temperature in the first zone ranges from about 170 to 210° C. 
     
     
       10. The method of claim 1 wherein the selected reaction time in the first zone ranges from about 30 to 120 seconds. 
     
     
       11. The method of claim 1 wherein the controlled temperature in the second zone ranges from about 250 to 290° C. 
     
     
       12. The method of claim 2 wherein the heating of the liquid slurry soap mixture in the second apparatus ranges from about 280 to 320° C. and 1 to 10 mm mercury absolute pressure. 
     
     
       13. The method of claim 4 wherein the yield of free sterols from the feed material is greater than about 90 percent by weight. 
     
     
       14. The method of claim 1 wherein the feed materials comprise over about 50 percent by weight of sterol esters, and the free sterols product comprises sitosterol, campesterol, and stigmasterol. 
     
     
       15. A method for the reaction and concentration of a liquid, organic, saponifiable material and a nonsaponifiable material feed mixture, which method comprises: a) providing a first, rotary, generally horizontal, thin film apparatus having a one end and an other end and having two external jackets to provide a first, thin film reaction zone and a second thin film evaporation zone;   b) introducing the feed mixture into the reaction zone;   c) introducing an alkali as a reactant feed stream into the reaction zone to saponify the saponifiable material, to provide a reaction mixture from the reaction zone comprising an alkali-saponified product, the nonsaponifiable material, and a volatile liquid comprising water and hydrocarbons;   d) evaporating the volatile liquid from the evaporation zone alone as a vapor; and   e) withdrawing the alkali-saponified product and the nonsaponifiable material from the evaporation zone.   
     
     
       16. The method of claim 15 wherein the feed mixture comprises a vegetable or plant oil product which contains fatty acids, fatty oils, and sterol esters or free sterols. 
     
     
       17. The method of claim 15 wherein the alkali comprises an aqueous solution of an alkali or alkali earth hydroxide. 
     
     
       18. The method of claim 15 which includes heating and separating the withdrawn saponified and nonsaponified material, to provide a saponified product material and a nonsaponifiable free sterol product. 
     
     
       19. A method for the saponification, evaporation, and separation of a liquid plant mixture comprising saponifiable fatty material and nonsaponifiable sterols, which method comprises: a) carrying out in a thin film on the walls of an evaporator, a saponification reaction of the plant mixture with an alkali solution to provide a reaction mixture comprising a fatty soap product, volatile by-products, and free sterols;   b) evaporating the thin film reaction mixture and discharging the volatile by-products from the evaporator;   c) discharging from the evaporator, the soap by-products and free sterols as a liquid slurry.